PURPOSE: To improve the accuracy of measurement by changing reception sensitivity rapidly and surely according to the distances between stationary antennas and buoys in a receiver for a river flow rate measuring system using a radio buoy.
CONSTITUTION: The section of a river is divided to plural water flow blocks, and the sectional areas of these blocks are beforehand obtained. On the other hand, the pass time of a radio buoy charged into each block for a fixed distance is obtained from the time difference detected with two antennas and the flow rate of the river is determined from the above pass time. Here, the distance between the buoy and the antennas differs with the block near the bank and the block further therefrom and therefore the signal reception levels fluctuate. Thereupon, every time when the buoy is charged successively in the blocks, a switch 11 is pressed and the fluctuations in the reception signal level are eliminated by a count part 10 corresponding block numbers and count values iB, a control part 10 outputting the voltages Vc corresponding to the block numbers of the buoys and a receiver 30 of which the gain is controlled according to said voltages.
OOISHI KATSUO
NORIKANE TOSHIO
